So many Outlooks. So much confusion.

The short answer is: Outlook and Outlook.com are two three different things. They don’t really relate to each other.
They have only three things in common: they’re all related to email, they all have the word “Outlook” in their names, and their icons are similar if not identical.
That’s where the similarity ends. It’s frustrating because people often refer to Outlook when they mean Outlook.com.
Oh, and as of this writing (in September 2023), it’s gotten worse. There are now two Outlook desktop email programs. And, you guessed it, they are completely separate from one another.
Let’s wade into the mess.
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Outlook vs. Outlook vs. Outlook.com
- Outlook is an email program you install on your computer and is part of Microsoft Office / Microsoft 365.
- Outlook for Windows is an email program that will apparently replace the default Mail and Calendar app in Windows 10 and 11 and is beginning to be rolled out in 2023.
- Outlook.com is a website and online email service provided by Microsoft.
- Outlook, Outlook for Windows, and Outlook.com are three completely different things.
Outlook (the program)

Outlook, which I now often refer to as “Microsoft Office Outlook“, is:
- Software you install onto your computer.
- Part of Microsoft Office (aka Microsoft 365), which is a purchased product.
- An email program that downloads your messages to the computer on which it’s installed.
- Able to connect to any email account or service providing POP3 or IMAP interfaces (which is most).
- A fully featured personal information manager (PIM) with address book, calendar, to-do list, and more.
- Extensible, meaning Outlook can be extended via add-ins and macros.
Outlook (the other program)
When running the Mail program in Windows 10 and 11, you may see a notification.

The “Outlook” being referred to by this message is not Microsoft Office’s Outlook, but a completely different Outlook. From what I can see, it’s often referred to as “Windows Outlook“, so that’s how I’ll refer to it.
Windows Outlook is:
- Software you install onto your computer.
- An email program that downloads your messages to the computer on which it’s installed.
- Able to connect to any email account or service providing POP3 or IMAP interfaces (which is most).
- Includes an address book, calendar, and to-do list.
- Free.
You can have both these Outlooks (Microsoft Office Outlook and Windows Outlook) installed on your machine, and both will appear if you search for “Outlook”.

You can even run both at the same time.

As you can see, they appear to be very, very similar. Running them side by side, you can see some differences.

The easiest difference for me to remember is that Microsoft Office Outlook has a File menu and Windows Outlook does not.
Outlook.com (the website)

Outlook.com is:
- A website you visit using your web browser, such as Edge, Firefox, Chrome, or any other.
- An email service on which you can create your own free email address ending in outlook.com.
- A replacement for Hotmail.com.
- A web-based user interface used to access only existing Hotmail (and other Microsoft) email accounts.
- Free.
As you can see, Outlook.com doesn’t relate to Outlook other than having a similar appearance to Windows Outlook.
Microsoft Office Outlook and Windows Outlook are email programs you install on your PC; Outlook.com is a website you visit in your browser to access email.
The only thing Outlook.com shares with Outlook is the word “Outlook” (and the icon), which is apparently Microsoft’s attempt to create some kind of generic branding for anything email-related (thoroughly confusing users in the process).
Outlook Express
I have to include Outlook Express for completeness. Even though it’s long, long dead, its memory lingers on.
Outlook Express was:
- A program you installed on your computer.
- Free; it was included on most Windows installations before Windows Vista, and came with Internet Explorer versions 6 and earlier.
- An email program that downloaded your messages to the computer on which it was installed.
- An Internet news reader, as it accessed Usenet newsgroups and other older Internet news servers.
- A contact list manager aimed primarily at managing contacts specifically for mail and news.
- Completely unrelated to Microsoft Office Outlook.
I say “was” because Outlook Express has been DISCONTINUED. Outlook Express was discontinued by Microsoft years ago and wasn’t included in Windows versions beginning with Vista. In fact, Outlook Express will not run on Windows 7 or later.
Based on my experience answering questions and trying to help people with Outlook Express, my position is that it is long past time to move on and select another email program.
Do this
So which Outlook do you want?
Microsoft Office Outlook is a powerful email program targeted at the business environment, email power users, or those who want the additional features it brings. With a lot of support from third-party vendors including things like mobile device synchronization, Outlook is a reasonable choice for the home or casual user.
Windows Outlook looks to be the future of the email program to be included in Windows. It’s free, looks reasonably well-featured, and is likely to improve over time. If your needs are simple and you want a desktop email program, this is a reasonable choice.
Outlook.com is a fine web interface for accessing your Microsoft account-related email. It can be the primary means for accessing your outlook.com, hotmail.com, live.com, msn.com, or any number of other Microsoft-provided email services.
Outlook Express is no longer an option.
Regardless of which Outlook you choose, use it to subscribe to Confident Computing! Less frustration and more confidence, solutions, answers, and tips in your inbox every week.
Footnotes & References
1: Of interest on close inspection is the “try the new Outlook” in Microsoft Office Outlook, which switches you to… Windows Outlook.
Leo, Why not dedicating a few words to the Mail App? The latest version is easy to remember: 16005.12228.20356.0
Leo has recommended the Windows Mail App in a Tip of the Day. It can be just right for someone with basic email needs.
Hi Leo
I just did not understand anything you wrote about ‘Outlook’ and ‘Outlook.com’!
I only know that my Outlook email is names ‘https://outlook.live.com’, but you
did not say anything about this ‘Live’ please enlighten me if possible, thanks.
Kind Regards
Allan
https://outlook.live.com is the same website as https://outlook.com. When you enter https://outlook.com, it redirects to https://outlook.live.com automatically. The URL (website address) is a kind of address forwarder to the real web address which is the IP number. The URL goes through a Domain Name Server (DNS) which is an index connecting the URL to the IP address and sends you to the correct page.
Leo,
Thanks for the explanation BUT, now I am totally confused, as I was going to write you about this before and now with what you just published, it’s time for me to ask what is it that I have: https://outlook.live.com/owa/? I wrote to Outlook asking if what I had was current and, never received a response back from them, assuming that they are not running at peak efficiency due to the Pandemic. Any insight, as to what I have and whether this is current, would be appreciative.
When you visit outlook.com you’re redirected to outlook.live.com — “owa” stands for Outlook Web Access. You have outlook.com.
Hi. I have been with Outlook for years, as I didn’t like the format that Gmail had, so my son set me up with Outlook Express which just simply gives me a column list of all emails- great.
Over the years we have gone from Windows XP to Window 10 and everything continued ok.
I cant remember whether Outlook Express automatically changed to just Outlook or whether my son did the change.
Anyway, I can’t open my latest emails, because Microsoft throws up a window, saying, “too many messages- need to delete some”. When I go to delete some, same window pops up, so I’m totally jammed.
Contacted Microsoft and after a few question, they directed me to their Tech person, and told to join up and subscibe to $70 mth. Pardon – though Outlook was free, or has been all these years. Any ideas.
Outlook Express was an email program which was included in XP. Outlook is not free. It’s a part of Microsoft Office and has to be set up explicitly with your email login credentials to work. So it looks like your son set it up for you. The too many messages, most likely, comes from your email provider and not Outlook, itself, even though the messages appears when you use Outlook. I’d go to my email provider’s website and delete the excess emails there and see if that solves the problem.
I suspect he’s referring to Outlook.com – not Outlook.
I thought he meant Outlook from Office because he mentioned Outlook Express. This is an example of Microsoft’s lack of understanding how to come up with unambiguous names for their products.
My guess is you did not actually contact Microsoft, but someone posing as Microsoft. (Depends on how you found the contact info — there are a lot of scammers.)
It will be VERY important to know EXACTLY what email interface or program you’re using — browser, which one, or email program like “Mail” in Windows 10. Be sure to understand that, because it’ll be the very first question you’re asked. You might also screenshot that “too many messages” message. Here’s how to contact Microsoft Support (be forewarned, options are limited): How Do I Contact Outlook.com Customer Service? Of course you can also reach out to https://askleo.com/ask .
If Microsoft removed the ability to add other email accounts to Outlook.com, does that mean that you also cannot add them to the app which I thought was totally separate from Outlook.com? I have been unable to add new accounts to the Outlook app on my computer for a while now. When it gets to the final phase of the adding process it just hangs on “We’re getting things ready…” and nothing ever happens. No error messages, nothing. I have to cancel the process. However, if I use the mail feature on my Windows 10 machine, it has no problem connecting to the email account. I just want all my emails in ONE app though…
Outlook.com and Outlook, the app, are unrelated. So what happens in one has no bearing on what happens in the other.
Outlook, the app, should support multiple accounts. You might try repairing office, or reinstalling it.
I have an outlook.com address set up by the person who installed Office on my new computer three years ago. I have had a hotmail.com address since the 90s. I have also purchased 365 for the storage and to not risk losing anything I’d done in Word and Excel over the years.
My hotmail.com address is receiving notifications that I will soon be over the storage limit as they combine it with OneDrive and I will have to buy 365 to avoid paying for storage. My outlook.com email address does not receive these notifications. As I said before, I already purchased 365. How do I reconcile the two account so that Microsoft doesn’t double charge me?
Free up space in the account that’s throwing the error. That means deleting things from OneDrive and/or deleting (or downloading) emails with attachments that are adding up to take all the space.
More here: https://askleo.com/why-is-my-outlook-com-email-suddenly-full/